Pump



y 1950 c. s. SORENSEN 2,506,974

PUMP

Filed Nov. 14, 1944 I s Sheets-Shet 1 y 9, 1950 c. s. SORENSEN 2,506,974

' PUMP Filed Nov. 14, 1944 6 Sheets-Sheet 3 May 9, 1950 c. s. SORENSEN PUMP I/IlUEIltO'l y 1950 c. s. SORENSEN 2,506,974

PUMP

NOV. 14, 6 sheets-sheet 5 May 9, 1950 c. s. SORENSEN PUMP ' 6 Sheets-Sheet 6 Filed Nov. 14, 1944 IN VEN TOR. CZa/wnu/A Mun am Patented May 9, 1950 UNITED STATES PATENT OFFICE PUMP Clarence S. Sorensen, Los Angeles, Calif.

Application November .14, 1944, Serial No. 563,335

Claims. 1

My invention comprises a pump, more specifically a pump for use in hydraulic systems in aeroplanes. Such pumps are used to motivate landing wheels, landing flaps, and other devices.

Pumps of the present type for use in this field are what are known as gear pumps. These pumps are capable of giving a hydraulic pressure in the system of approximately one thousand pounds to the square inch. In modern planes it has become desirable to raise this pressure, and a pump is required that will give up to three thousand pounds per square inch. A pump constructed in accordance with my invention is capable of delivering pressure up to three thousand pounds per square inch. As these pumps are directly driven from the engine of the plane, they must be self-regulatory. A pump constructed in accordance with my invention can be set to deliver any desired pressure, and will maintain that pressure automatically.

Another advantage of my invention is the complete absence of gears or reciprocating parts other than pistons themselves. All motions in the pump are revolving motions, preventing wear and decreasing vibration.

Another advantage of my pump is that all parts are completely lubricated by the fluid in the hydraulic line.

Another advantage of my invention is that it can be made of a very light weight and of light materials such as aluminum as the forces therein are so balanced as to prevent the necessity of heavy duty bearings.

Another feature of my invention is that my pump is of the variable displacement type and has an automatic control system incorporated therein whereby it delivers its maximum capacity at or near its maximum pressure, but upon nonuse of the pressure to operate the landing gear, etc., the capacity is automatically reduced, thus giving longer life to the pump.

Other advantages of my invention will be apparent from the following description in the preferred embodiment thereof.

In the drawings:

Fig. 1 is an end view of my pump.

Fig. 2 is a cross-section taken on the line 2-2 of Fig. 1.

Fig. 3 is a cross-section taken on the line 3-3 of Fig. 2.

Fig. 4 is a cross-section taken on the line 4-4 of Fig. 2.

Fig. 5 is a section taken on the line 55 of Fig. 4.

Fig. 6 is a cross-section taken on the line 8-6 of Fig. 2.

Fig. 7 is a partial section of my pressure pump showing a different valve arrangement.

Fig. 8 is a cross-section taken on the line 8-8 of Fig. 7.

Fig. 9 is a section of a modified form of breather valve.

Fig. 10 is a section showing a modified form of bearing on the intake side of my pump.

Fig. 11 is an end view of a modified form of my pump.

Fig. 12 is a section taken on the line l2l2 of Fig. 11.

Fig. 13 is a section taken on the line I 3-13 of Fig. 11.

Fig. 14 is a schematic moment diagram.

A pump constructed in accordance with the preferred type of my invention consists of a housing I and a cover 2. The housing I and the cover 2 enclose a central cavity 3 and have at each end of this cavity seats 4 for the reception of ball bearing races 5. The ball bearing races 5 comprise bearing surfaces for the tubular shaft 6 which is journaled therein and free to rotate. 1

At one end of the shaft are the splined teeth 1 which cooperate with the splined teeth 8 on a stub shaft 9. At its outer end the stub shaft 9 carries the teeth or other means for connecting to a prime mover to drive said stub shaft 9 and tubular shaft 6. The stub shaft 9 has a reduced cross-section II which is ground down so that if the pump jams, the stub shaft will snap off at this reduced section and not injure the prime mover. As the main intake to the pump is through the threaded bore l2 in the cover 2 into the center of the tubular shaft 6, the other end of the pump must be sealed to'prevent any discharge of hydraulic fluid. To accomplish this I provide the end plate I3 which is a force fit in the end of the tubular shaft 6, and to further seal the power driving end of the pump a cover I4 is bolted to the housing. In the bore [5 through the end of the cover I4 is positioned a bronze bushing l6. Between the bronze bushing l6 and the cover I4 is placed a sealing ring ll made of rubber, neoprene, or other resilient sealing material. The inner face I8 of the bronze bushing I6 is ground and lapped to engage a ground and lapped surface I 9 on a hardened steel bushing 20 carried by the stub shaft 9. Between the bushing 20 and the stub shaft 9 is positioned a sealing ring 2| similar to the sealing ring ll. Both of the rings I! and 2| are oversize and make a tight flt which causes the bushing l6 to remain stationary in relation to the cover I 4 and the bushing "to rotate with the shaft 3. The stub shaft 3 has a bore 22 in which is positioned a spring 23. This spring 23 engages the outer surfaceof the plate I3 and urges the stub shaft outwardly from the pump. This forces the surfaces l3 .and is into continuous engagement. The sealing rings l1 and 2| provide resilient means which allow the bushings I 6 and 20 to seat tightly against each other and prevent any leakage from the interior of the pump through the here It.

The tubular shaft 6 carries a cylinder block 24 which may be an integral part of the tubular shaft or a separate piece which is a force fit upon the shaft 6. The cylinder block 24 is bored in a radial form to have a plurality of cylinders 25. In a preferred form of my invention, I have an odd number of cylinders, such as seven or nine, and stagger the cylinders in one bank in relation to those in the other. The cylinders are arranged in two banks to provide two separate radial series of cylinders. Surrounding the cylinder block 24 are antifriction bearings 26 which are slidably carried by the housing I. Each of the bearings 26 is free to slide independently of the other, and the housing i carries the squaredoff plates 21 so that they can only slide in one direction in the central cavity 3.

The pistons 23 are carried in the cylinders 25 and each piston 23 has at its outer end a ball 29 for engaging the inner surface of the bearing 23 and absorbing motion which would be transmitted to the ends of the pistons. This ball may be spun into the end of the piston to maintain it in position, but it must be free to rotate therein to reduce friction between the piston 23 and the bearing 26. The centrifugal force applied to the pistons as by rotation of the tubular shaft 4 causes the pistons to be forced against the bearing 26. To secure a positive alignment, less friction, and better contact between the balls 26 and the bearing 26, a semicircular groove is placed in the bearing race 26 for the reception of the ball 23. To cause the pistons 23 to reciprocate in the cylinders 26, the bearing races 26 are slid eccentric to the main shaft 6. To reduce vibration and to balance the pump, I displace on opposite sides of the shaft 6 the bearing races 26. This causes one bank of pistons to oppose the action of the other bank.

At each end of the cylinder block 24 is positioned a valve body 30. It is preferred that the cylinder blocks and valve body he made of dissimilar metals to reduce friction and wear. The valve bodies have the surfaces 3| which are ground and lapped to engage the ground and lapped surfaces 32 on the cylinder block 24. In a pump of the preferred type, the valve bodies 33 have substantially /12 of an inch clearance between their inner surfaces and the tubular shaft 3, and are free to slide thereon. Though the valve bodies 36 are free to slide longitudinally on the shaft 6, they must not rotate thereon; and I provide the pins 33 in the housing I and the cover 2 which engage the bores 33a. The bores 33a are elongated to permit the valve body 30 to slide, but do not permit any rotation when the pin 33 is inserted in the bore 33a.

The tubular shaft 6 carries a series of ports 34 around its periphery which open into the ports 36 in the valve body 30. The cylinder block 24 has ports 36 which open into the cylinders 26. On the opposite side from the port 36 is a relief 4 area 33 to equalize the hydraulic pressure and prevent a tipping of the pistons 23. The low pressure line or feed to the pump threadably engages at l2 the cover 2 and permits the hydraulic fluid to enter the center of the shaft 6. Upon rotation of the shaft 6 this fluid passes through the ports 34, 36 and 36 into the cylinders 25. when the bearings 26 are eccentrically positioned in relation to the shaft 6, and the shaft 6 rotated, the pistons 23 follow the bearings 26 and in onehalf of the rotation the pistons travel outwardly in the cylinder, causing a suction stroke which draws the hydraulic fluid into the cylinder.

Upon the other half of the rotation, the pistons are forced inwardly by the bearing 26, causing them to force the hydraulic fluid outwardly through the ports 31 in the cylinder block into the ports 33 in the valve body 33 into the bore 33, and then outwardly through the discharge 43.

To provide lubrication for the ball 26, an oil hole 4| connects with the socket in which the balls 26 ride. While the piston is being actuated, this oil hole 4i connects with the bores 36 and 31, but only 011 from the high pressure discharge port 31 will enter this oil hole.

As the two banks of cylinder blocks are loaded, and therefore exert a pressure on opposite sides of the shaft 6, this force sets up a turning moment to the shaft 6. Lighter and smaller bearings 5 can be used if this momenet is reduced. I have found that by applying the hydraulic force of the fluid discharged to the ends of the valve bodies 30, I can overcome this torque and at the same time secure a sealing flt between the faces" and 3|. To accomplish this desired result, I provide a series of valve balance pistons 42 mounted in the valve body 33. These pistons have a button 43 which presses against the outer face 44 of the bearings 6 which engage the housing l and the cover 2 upon their opposite sides. The hydraulic pressure upon the pistons 42 causes a force to be exerted against the bearings 6 and the outer housing, which forces the valve body 33 inwardly into sealing engagement with the surface 32 of the cylinder block.

The pump constructed in accordance with the preferred embodiment of my invention is designed to deliver a pressure of 3000 pounds per square inch. At this pressure there is a force between the surfaces 3| and 32 of approximately 2070 pounds. This is caused by the forming of I .causing the high pressure side to lean away from the cylinder block, and the low pressure side to rub tightly against it. To overcome this tendency the pistons 42 are exposed to the high pressure fluid and exert a pressure against the outer bearing face 44. The positioning and the size of the pistons 42 cannot be determined mathematically, but must be determined by experimentation so that the force delivered by them will cause a force on the same center line as the force created on the half of the valve which is subject to the high pressure fluid.

In the diagrammatic Figure 14 is shown a moment diagram of the forces exerted on my pump.

In this diagram the letter A represents the direction of the force set upon the main shaft 6 by the force of the pumping pistons. The value of this force is approximately 1000 pounds. The point lettered B represents the center or turning point around which the forces A tend to turn the main shaft 6. C represents the point above the center line of the valves 30 at which the high presure fluid exerts the force of 2070 pounds. This pressure which tends to spread the valve and the cylinder block is overcome by a force exerted at E on the valve balancing pistons 42 which press against the bearing race 4 and the outer cover of the pump. The pressure exerted upon the piston 42 will overcome the force exerted at C. This force is in the opposite direction to the moment set up by the forces A, and will substantially equalize it, thus relieving the moment directed to load the bearings 5. An important matter of my invention consists in the fact that I use two oppositely opposed sets of cylinder bores. If only one set of cylinders in a single block were used, the pressure of 2070 pounds would be exerted entirely into forcing the cylinder block against the end bearings, thus requiring a heavy thrust bearing that would be capable of not only absorbing 2070 pounds, but also any added pressures caused by the unbalanced force delivered by the pistons themselves. By the use of two sets of cylinders in an opposite direction and the valve bodies which are free to slide and always maintain perfect sealing condition and loaded by the high pressure fluid, the entire size and weight of all bearings and parts can be reduced.

When the pump is first started at very slow speeds, the surfaces 3| and 32 tend to separate because of the lack of pressure on the piston 42 to force them into sealing engagement. To make my pump self-priming, I incorporate the springs 45 which exert a force on the valve body and against the inner surface of the pistons 42, thus sealing at all times the surfaces 3| and 32 together. To prevent leakage around the exterior of the valve body 30 and at the same time allow them to slide or to align themselves, I provide the rubber doughnuts 46 in the grooves 41 which are a tight fit on the inside of the groove 41 on the periphery of the valve body 30. Of course. the doughnuts 46 can be formed of either natural or synthetic rubber, or any other resilient sealing substance.

In Figures 7 and 8 I show a modification of my invention which comprises all of the essential elements of the preferred form shown in Figure 1, with the exception that a different type of valve body 30 is used. In Figure 7 the valve body 30a is similarly mounted between the bearings 5 and the cylinder block 24 and has the same rubber doughnuts 46 and grooves 41 to prevent leakage. In this form of valve the pressure of the discharge exerts its force on the lunar face 5| which has the same effect on the valve as the pistons 42 in Figure 1. The surface of this lunar face 5| has an area and is positioned to cause the center of moment of the force exerted by the pressure to be in substantially the same position as the center of moment created on the pistons 42. In the modification shown in Figure 7, to secure a pressure when first starting or running under a light load, I provide the spring 52 equally spaced around the face of the valve body 30a in the socket 53 which press upon the valve body 30a and upon the plate 54 which contacts the bearing race 5 on its opposite side. The spring 53 exerts a pressure upon the valve to keep the surfaces 31 and 32 in sealing engagement. In the valve body 30a are ports 55 similar to the bores 38 in the valve body 30a through which the pressurized fluid leaves the cylinders 25.

In Fig. 10 is shown a modification of my invention which comprises all of the essential elements of the preferred form shown in Fig. 1 with the exception that the bearing races 5 have been deleted. In their place the valve bodies 30 comprise the bearing surfaces for the main shaft 6 as there is no end thrust on my pump because of the double bank of cylinders. No provision is necessary for end thrust. The inner face of the valve body 30 is faced with a bearing material I50 to absorb the light thrust placed thereon during the action of the pump.

An advantage of my pump not present in most hydraulic pumping systems for use in aeroplanes is the fact that the tubular shaft 6 is directly ported to the cylinders. This causes the fluid in the low pressure line which enters the center of the tubular shaft 6 to be hurled out by centrifugal force through these ports, thus causing a supercharging effect. As the low pressure line is usually subject to the atmospheric pressure at which the plane is, this supercharging effect maintains the pump in its usual operating efficiency at all altitudes and requires no booster. However, I have found that it is sometimes desirable to further supercharge the intake of my pump by the use of an axial flow impeller 10 which is fixed in the end of the tubular shaft 6 and rotates therewith causing the oil in the low pressure line to be forced inwardly into the tubu lar shaft causing a pressure in that shaft which when combined to the centrifugal force highly supercharges the intake of the pump, greatly increasing its efllciency at high altitudes.

A feature of my pump is that it is what is known as a variable displacement pump, i. e., that it maintains a substantially constant pressure and at the same time a variable amount of fluid can be delivered to' the hydraulic system.

. The control system which is to be hereinafter described provides a cushioning effect which prevents any knocking or shocks to the high pressure hydraulic system. To automatically control pressure and volume delivered, I provide a cap (Fig. 3) which is threaded into the housing I and has a bore 8| therein for the reception of a piston 82. Pressing against the interior of the cap 80 and the head of the piston 82 is a spring 83. Piston 82 is maintained in contact and exerts a pressure upon the bearing races 26 which normally tends to move the bearing race 26 into an eccentric position in relation to the shaft 6.

When the only load on the bearing race 26 is caused by the spring 83 and the piston 82, the bearing race 26 is pushed to its most eccentric position and the pump has its greatest displacement. To decrease the displacement of the pump, I provide a fitting 84 threaded to the housing I directly opposite the cap 80. The fitting 84 has a bore 86 therethrough in which is positioned a piston 85 which contacts the bearing race 26. In the bore 86 is positioned a second piston 81 which is maintained in position by the spring 88 placed between one end of the piston 81 and the constriction 89. Threaded to the fitting 84 is a cap 90 which has a port 9| therethrough with a ball valve seat 92 adjacent the end of the piston 81. A socket 93 is provided in the end of the piston 81 for the reception of a ball 94. Ball 84- acts as a ball relief valve to close the port 9 I. The

draulic fluid under the high pressure delivered by the pump exerts a pressure upon the ball 84 which when it has reached the desired maximum will open the port BI and allow the hydraulic fluid therein to flow through the spaces 88 between the piston 81 and the sides of the port 88, placing pressure upon the piston 85 which will overcome the pressure of the spring 88 and force the bearing race 28 into substantial concentricity with the main shaft 8, cutting down the displacement of the pump.

A feature of this control is the fact that the spring 88 can be set so that the pump delivers its maximum displacement until the pressure in the high pressure line reaches substantially the preferred pressure of 2700 pounds, whereupon the ball 94 is unseated and the oil seeps past piston 81 and exerts pressure upon the piston 85. This seepage prevents a sudden thrust against piston 85 and prevents a knocking in the high pressure line.

As the spring 88 is set to allow the ball valve ,84 to open only when the pressure rises to substantially 2700 pounds per square inch, there is no tendency of the pressure in the line to urge the piston 85 inwardly and decrease the capacity of the pump until substantially the maximum pressure exerted by the pump is achieved. This gives a curve of capacity and pressure ratio which is substantially Straight until a very high pressure is achieved and allow the pump to deliver full capacity at such pressure. Operation of the landing gear on a plane will not cause the pressure in the line to drop substantially as a slight drop causes the valve 84 to seat and maximum capacity of the pump would be delivered. Sudden shifting to full capacity of the pump would cause knocking and is prevented by the fluid trapped in the bore 88 by the closing of the ball valve 94. This fluid acts as a cushion to the sudden return of the piston 85. To permit the piston 85 to return the same is made a few ten-thousandths of an inch smaller in diameter than the bore 86, allowing the fluid to seep past into the housing I.

As it is sometimes desirable to stop the pumping action when, for example, the line from the pump has been punctured by any cause whatsoever, I can modify my pump with a remote control device which can be positioned where a pilot can operate the same. Such a control consists of a body IOI (Fig. 9) into which is threadably secured the valve I02 which has a seat I03 and a ball valve I04 riding on the ball carrier I05 which is forced into a seating position by the spring I06. The tension on the ball valve I04 can be adjusted by the set screw I0I. When it is desired to shut down the pump entirely, said screw I0! can be turned out to its fullest extremity, thus unseating the ball I04 from its seat I03. When this valve is used, the port I08 is connected to the high pressure line on the plane's hydraulic system and the port I09 is connected to a line which runs to the fitting 84. In this case the piston 81 and the ball valve 84 are dispensed with so that fluid imported through port I08 acts directly on the piston 85 which forces the bearing race 26 into concentricity, cutting the displacement of the pump to zero. Said screw I01 can be set to cause the pressure of the spring I08 on the ball I04 to any pressure and it is preferably set so that the spring I06 exerts the same pressure as would the spring 88. In fact, this remote control is merely an adjustable means of accomplishing-the identical results as those achieved by the spring 81 and ball 84.

To prevent the necessity of using a very heavy spring 88 and a very large piston 88 and also to minimize vibration set up by the pressure in the pumping cylinders which would tend to vibrate the bearing race 28, I rotate the ports in the valve body 30 5 to 9 from their center line so that the discharge is slightly early and places a pressure on the bearing race 28 which tends to always maintain it in eccentricity and relieves the force on the spring 88 and also minimizes vibration of the bearing race 28.

The action. of the pistons and the valves squeezes the oil and creates therein friction which raises the temperature of the pump materially when rimning at full pressure and low capacity. To prevent this, I have provided a continuous flow of oil through the pump. When the storage tank from the pump is below the pump, it is connected through a drain fitting 88 attached to the cap which forms a port through which the 011 within the housing I may drain. This flow is caused by the fact that the bearing surface of the valve body 30 is made in lands as with gaps I00 between them. These gaps provide a passage for the oil from the shaft 8 out into the outer cavity where it may pass through the fitting 88. Also oil leaks out of the cylinders and valves into the housing I. However, when the pump is mounted below the storage tank, it is necessary to close the gaps I00 at the points I 00a, and then the flow is only from leakage forced out by the pistons and valves into the housing, but this leakage is sufficient to maintain the pump sufllciently cool. This leakage builds up a pressure in the housing and a relief check valve is placed in the position of the fitting 98 which when the pressure is built up sufllciently allows the pump to force the oil back into the storage tank through a relief check valve positioned in the place of the fitting 88.

A further modification ofmy invention is disclosed in Figs. 11, 12 and 13. In aeroplanes operating at great altitudes, the atmospheric pressure is so greatly reduced that the pressure on the oil supply system on the intake end is reduced and starves the pump. Attempts have been made to use pressurized reservoirs to minimize cavitation. However, in event this system fails, I have equipped my pump with a supercharger which consists of all of the previously described elements of my pump except that the cover 2 is replaced with a cover IIO which contains the bore III and a cross-bore II2 sealed by a circular band II 3. Journaled in the bore III is a gear I I4 which meshes with the gear I I5 attached to the tubular shaft 6 by the spline teeth IIB. These gears are driven by the shaft 6 and act as a ear pump which is not damaged by starving. Bores III and II! are lined with liners II! of dissimilar metal from that of the gears H4 and H5. If the gears H4 and H5 are made of steel, the liners II'I should be of bronze. These liners fit securely against the sides of the gears II 4 and I I5 and prevent leakage of hydraulic fluid. The end of the tubular shaft 5 connects with a passage H8 in the cover plate H8. The passage I I8 receives the hydraulic fluid forced out of the gear pump. The threaded bore I20 comprises the intake. As this gear pump, or supercharger, is always pumping when the shaft 8 is rotated and the main pump may be in its concentric or non-pumping position, I provide a relief valve on the passage H8. A spring I22 maintains the check valve I23 in its seat I24. I prefer to adjust tension on this spring to maintain the valve I23 seated until the pressure exerted on the valve is between to pounds per square inch, or other desired pressures, when the valve opens and permits the fluid to pass through the passage I25 back into the intake port When this supercharging gear pump is incorporated, I have found it desirable to form the lands 99 continuous and dispense with the gaps 100a to prevent too high a flow of oil into the housing I. Suflicient cooling and lubrication is secured by the leakage forced out of the pistons and valves.

While I have disclosed the preferred embodiment of my invention, I am not limited by any of the details of construction herein set forth except as described in the following claims.

Iclaim:

1. In a pump, a housing, valve bodies carried by said housing, a shaft journaled in said housing and carrying a cylinder block, said block having a plurality of cylinders radially extending from said shaft in a plurality of banks, pistons in said cylinders, bearing means on the outer side of said pistons to engage a plurality of bearing races slidably carried by said housing, means for sliding said bearing races into eccentric position, in relation to said shaft, said bearing races being oppositely eccentric to minimize vibration and substantially balance said pump, said valve bodies having an area on the same side of said shaft to the compression side of said cylinders upon which the pressure exerted by the discharge substantially counteracts the moment set up by the compression in said cylinders, to substantially balance hydraulic forces of said pistons and said valves, thereby reducing loads on said cylinder block journals.

2. In a pump, a housing, a tubular main shaft carrying a cylinder block, cylinders in said block, valve bodies carried by said housing, ports in said valve bodies to align with ports in said shaft and in said cylinder to admit fluid to the cylinders in said cylinder block, ports in said valve bodies aligning with ports in said cylinder block and said housing to permit discharge of fluid from said cylinders, bearing races slidably carried by said housing, pistons in said cylinders having means for engaging said bearing races whereby when said bearing races are moved into eccentric positions with relation to said shaft, said piston will follow said eccentrically positioned race, caps carried by said housing forming cylinders for the reception of pistons which bear on said eccentric races, a spring positioned in said caps exerting pressure upon said pistons tending to force said bearing races into eccentric positions, caps carried by said housing on the opposite side from said first caps forming eyl inders for pistons which bear against said bearin races and tending to force said bearing races into concentricity, means for porting the discharge of said pump into contact with said last named pistons whereby said discharge can move said bearing races into concentricity with said main shaft to control the capacity of said pump and means to counteract the torque imposed upon said shaft by the compression of said cylinders.

3. In a pump, a housing, a tubular shaft journaled in said housing and carrying a cylinder block, said block having a plurality of cylinders radially extending from said shaft in a plurality of banks, bearing races slidably mounted in said housing, pistons in said cylinders and having bearing means for contacting said bearing races, means for maintaining said bearing races in an eccentric position in relation to said shaft, said bearing races being oppositely eccentric, valve bodies carried by said housing at the ends of said cylinder block, means for maintaining said cylinder block and said valve bodies in sealing engagement, said means being operable by the pressure of the discharge of said pump.

4. In a pump, a main shaft carrying thereon a cylinder block, said cylinder block being bored to form a plurality of banks of cylinders, pistons in said cylinders actuated by running on eccentrically mounted bearing races,'said bearing races for each bank of cyllinders being oppositely eccentric, valve bodies mounted flush against said cylinder block at the opposite'ends of said cyllinder block with the surfaces of said valve bodies away from said cylinder block exposed to the pressure of the discharge from said pump whereby said discharge pressure counteracts the torque imposed upon said shaft by the compression in said cylinders, and maintains said valve bodies in sealing engagement with said cylinder block.

5. In a pump, a housing, a tubular shaft journaled in said housing and carrying a cylinder block, said block having a plurality of cylinders radially extending from said shaft in a plurality of banks, pistons in said cylinders, bearing means on the outer side of said pistons to engage a plurality of bearing races slidably carried by said housing, means for sliding said bearing races into eccentric position in relation to said shaft, said bearing races being oppositely eccentric, valve bodies mounted flush against said cylinder block at the opposite ends of said cylinder block with the surfaces of said valve bodies away from said cylinder block exposed to the pressure of the discharge from said pump whereby said discharge pressure counteracts the torque imposed upon said shaft by the compression in said cylinders, and maintains said valve bodies in sealing engagement with said cylinder block.

6. In a pump, a housing, valve bodies carried by said housing, a shaft journaled in said housing and carrying a cylinder block, said block having a plurality of cylinders radially extending from said shaft in a plurality of banks, pistons in said cylinders, bearing means on the outer side of said pistons to engage a plurality of bearing races slidably carried by said housing, and automatic means for adjusting said bearing races in eccentricity to said shaft, valve bodies carried by said housing at opposite ends of said cylinder block, both of said valve bodies having surfaces oppositely disposed from said cylinder block subject to the discharge pressure of said pump to impose torque upon said cylinder block to counteract the torque imposed upon said shaft by the compression of said cylinders.

'7. In a pump, a housing, valve bodies carried by said housing, a shaft journaled in said housing and carrying a cylinder block, said block having a plurality of cylinders radially extending from said shaft in a plurality of banks, pistons in said cylinders, bearing means on the outer side of said pistons to engage a plurality of bearing races slidably carried by said housing, and automatic control means actuated by the pressure developed by said pump to slide said bearing races to conbodies to align with ports in said shaft and in said cylinder to admit fluid to the cylinders in said cylinder block, ports in said valve bodies aligning with ports in said cylinder blockand said housing to permit discharge of fluid from said cylinders, bearing races slidably carried by said housing, pistons in said cylinders'having means for engaging said bearing races whereby when said bearing races are moved into eccentric positions with relation to said shaft, said piston will follow said eccentrically positioned race, and means for controlling the' eccentricity'of said bearing race, both of said valve bodies having surfaces in contact with said cylinder block, said valve bodies having surfaces oppositely disposed from said cylinder block subject to the discharge pressure of said pump to impose torque upon said cylinder block to counteract the torque imposed upon said shaft by the f compression of said cylinders.

9. In a pump, 'a housing, a tubularmain shaft carrying a cylinder block, cylinders in said block, valve bodies carried by said'housing at opposite ends of said cylinder block, ports in said valve bodies to align with ports in said shaft andin said cylinder to admit fluid to the cylinders in said cylinder block, ports in said valve bodies aligning with ports in said cylinder block and said housing to permit discharge of fluid from said cylinders, bearing races slidably carried by said housing, pistons in said cylinders having means for engaging said bearing races whereby when said bearing races are moved into eccentric position with relation to said shaft, said pistons will follow said eccentrically positioned race, and automatic controlling means actuated by the pressure developed by said pump to control the eccentricity and capacity, both of said valve bodies having surfaces in contact with said cylinder block, said valve bodies having surface oppositely disposed from said cylinder block subject to the discharge pressure of said pump to impose torque upon said cylinder block to counteract the torque. imposed upon said shaft by the compression of said cylinders.

10. In a pump, a housing, a hollow main shaft carrying a cylinder block, cylinders in said block, valve bodiw carried by said housing at opposite ends of said cylinder block, ports in said valve bodies to 811811 with ports in said shaft and said cylinder block to admit fluid to said cylinders, ports in said valve bodies aligning with ports in said cylinder block and said housing to permit discharge of fluid from said cylinders, bearing races slidably carried by said housing, pistons in said cylinders having meansfor engaging said bearing races, whereby when-said bearing races are moved into eccentric position in relation to said shaft, said pistons will follow said eccentrically positioned races, both of said valve bodies having surfaces in contact with said cylinder block, said valvebodies having surfaces oppositel disposed from said cylinder block subject to the discharge pressure of said pump to impose torque upon said cylinder block to counteract the torque imposed upon said shaft by the compression of said cylinders.

CLARENCE S. SORENSEN.

REFERENCES CITED The following references are of record in the file of this patent:

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